Lathe spindle



Jan. 1, 1946. J GALLOWY 2,392,037

LATHE SPINDLE Filed March 27, 1944 2 sheets-sheet 1 Jan. l, 1946. .1. c. GALLowAY LATHE SPINDLE Filed March 27, 1944 2 Sheets-Sheet 2 wm, bw @n w m -M lnwb mh w /yd\//y////////M/////VV////// y. a W a Z d ,G d e x fw Patented Jan. l, 1946 UNiTsD STATES` PATENT oFFic'E LATHE SPINDLE Jesse C. Galloway, North Little Bock, Ark.

Application March 27, 1944, Serial No. 528.310

(Cl. 82--33i 10 Claims.

This invention relates generally tothe class of Turning machines and relates particularly in improvements in tail stock spindles.

The principal object of the present invention is to provide improvements in tail stock spindles for all types of machines doing work between centers or needing a device to automatically adjust the pressure on the work, wherein an improved supporting means for a center point or revolving arbor is provided which permits automatic recession and advancement of the point as may be necessary as a result of changes in the temperature of the work in engagement with the center.

Another object of the invention is to provide an improved tail stock spindle structure for a turning machine in which a fluid cushion is provided against which the work engaging arbor or pointed member is yieldingly held. means being provided ior relaxing the uid pressure behind the point or arbor upon an increase of pressure against the point or arbor and for returning the cushioning :fluid behind the center or arbor upon relaxation of such pressure.

Another object of the invention is to provide r a turning machine tail stock spindle structure in which' the work engaging pin or arbor is yieldingly held at the desired pressure by a duid cushion, with means for indicating to the operator the amount of pressure he has at all times against the work.

The invention will be best understood from a consideration of the following detailed description taken in connection with the accompanying drawings forming a part of this application, with the understanding, however, that the invention is not conned to a strict conformity with the showing of the drawings but may be changed or modified so long as such changes or modifications are within the scope oi the appended claims.

In the drawings:

Figure l is a view in top plan of a tail stock spindle constructed in accordance with one embodiment of the invention, the tail stock or support being broken away and in section.

Figure 2 is a view in longitudinal section taken substantially on the line 2--2 of Figure 1, through the said one embodiment per se.

Figure is a view in longitudinal section of a second embodiment of the invention which is particularly suitable for precision work.

Figure 4 is a view in longitudinal section through a third embodiment of the invention designed particularly for small machines.

let

Figure 5 is a transverse' section on the line 5 6 of Figure 4.

Figure 6 illustrates in longitudinal 4section still another embodiment of the invention showing the same mounted in a tail stock for axial adjustment, with means for indicating the amount oi' pressure imposed on the center.

Referring now more particularly to the drawings the numeral I0, in Figure 1, designates a portion of a tail stock body in which the spindle unit, generally designated II, is mounted. The body IIl may be of any suitable design for the reception of a tapered spindle unit and since the particular form of the support for the spindle unit forms no part of the present invention no vdetailed illustration or description of the same is given or considered necessary.

One embodiment of the invention is illustrated in Figures 1 and 2. which embodiment makes use of a revolving center which is supported in suitable bearings and may be employed particularly for heavy work.

This embodiment of the spindle unit comprises a relatively long exteriorly tapered body I2 which is designed to be inserted into the tail stock tapered bore. The body l2 has formed therein from the forward or larger end, the straight bore I3 which extends throughout the maior portion of the length of the body and is closed at its inner end by the partition wall It.

Behind the partition wall I the body I2 is formed to provide a longitudinally extending uid relief chamber l5 and a fluid reservoir i6 which has communication with the chamber I5 by the small port Il.

The rear ends of the chamber I5 and reservoir i6 open through the end of the body and the chamber is closed by the valve adjustment screw I8 while the reservoir I6 is closed by the plug I9.

At its forward end the relief chamber I5 communicates with the rear end of the bore I3 through the small relief passage 20 and this relief passage is normally closed by the rearwardly opening relief valve 2l which is maintained seated by the valve spring 22, interposed between the valve and the adjustment screw I8. Thus it will be seen that the amount of pressure against the relief valve 2| from within the rear end of the bore I3. necessary to open the relief valve,- may be varied by means of the adjustment screw I8.

Formed through the wall I4 between the rear end 0f the bore I3' and the reservoir I6 is a threaded passage 23 in which is iitted the cage 24 for a puppet type valve 25, the head of which is within the bore I8 so that this valve opens toward the bore for the rlow of fluid i'rom the reservoir I8 back into the bore.

The forward end of the spindle body |2 has -turned thereon the exteriorly threaded flange 28 upon which is threadably mounted the ring 21 forming a part of a packing collar in which the packing is designated 28.

Slidably extended into the bore I3 through the packing is a longitudinally shiitable sleeve 29, the forward end of which is open while at its rear end it is closed by the end wall 38. This end wall of the axially shiftable sleeve 29 is spaced from the wall |4 so as to provide a fluid cushion chamber 9| which is lled with a suitable cushioning iluid which may be in the form of oil 'or any other suitable substance.

Within the chamber 3| there is mounted between the end 38 of the sleeve 28 and the wall |4, the expansion spring 32 which normally urges the sleeve forwardly to a predetermined position.

Within the sleeve 29 and at the rear end thereof, there is mounted a. ball thrust bearing 32 against which is pressed the inner end of a rotatable arbor 33 which extends longitudinally in the sleeve as shown. This arbor has at its forward end, the head 34, the diameter of which is substantially equal to the inside diameter of the sleeve so as to ilt snugly therein. This head terminates in the point 35 which engages the work.

Within the sleeve 29 the arbor 33 extends through and is supported in the roller bearing units 38 and 31. The bearing unit 38 hes immediately behind the head of the arbor while the unit 31 lies at the inner end of the arbor adiacent the thrust bearing 32.

Means is provided for lubricating the bearings by the provision of the oil passage 38 which opens at one end through the outside of the sleeve while at its inner end it discharges into the roller bearing 38.

In the use of the unit just described a piece of work is mounted between the tail stock center point 35 and the head stock, in the usual manner, the tail stock being adjusted to apply sumcient pressure to the work to maintain the latter in proper position.

It is well known of material considerable heat may be developed in the work which, of course. creates expansion and excessive pressure against the head and tail stocks. This is particularly true in connection with the roughing out of metal pieces. When such heat development results causing expansion oi the work, longitudinal pressure will be applied to the rotating arbor, as a result of which the sleeve 29 moves back against the resistance of the spring 3| and of the body of fluid housed in the chamber 3|. When sufficient pressure is developed against the body of iluid in the chamber 3| to overcome the resistance of the relief valve spring 22, the valve 2| will open and permit some of the uid to escape into the reservoir I6. Thus a substantially constant pressure will be maintained on the work in spite of the expansion thereof and as the work cools the arbor point will advance under the action of the compressed spring 3| so as to hold the same pressure.

In the embodiment of the invention illustrated in Figure 3, a non-revolving center or point is made use of. This form of the invention is especially suited for precision work and it does not permit warping or wobbling of the work.

In the embodiment or Figure 3, the tapered spindle body is designated 38 and has a separable rear end portion 39a which is threadably coupled with the forward end portion as indicated at 4d to clolse the rear end of the iiuid cushion chamber In addition to the chamber 4| formed in the rear end of the forward portion of the body 39, there is formed axially through the body a bore 42 in which is slidably mounted the center pin 43, the forward end of which is pointed as at 44 for engagement with the work. The rear end of this pin extends into the chamber 4| and has engaged therewith the spur 45 between'which and the adjacent end of the body portion 39a, is interposed the expansion spring 46 which constantly urges the pin 43 forwardly or outwardly. The rear portion 39a is formed to have the relief chamber 41 and the reservoir 48 therein. Both this chamber and reservoir open through the rear end of the body portion, the relief chamber receiving the valve adjustment screw 49, and the reservoir receiving the closure plug 50.

Communication between the relief chamber 41 and the reservoir 48 is by way of the small passage 5|.

The forward end of the chamber 41 has leading therefrom the relatively small passage 52 by which communication is had between this chamber and the fluid cushion chamber 4|. This passage 52 is closed by the valve 53 and this valve is maintained in closed position by the spring 54 interposed between it and the adjustment screw 49.

The reservoir 48 also has communication with 85 the rluid chamber 4| by means of the passage 53 which is normally closed by the outlet valve 54 past which the uid flows from the reservoir into the cushion chamber 4| when the pin 43 is returned to its initial position by the spring 46,

after being forced back against the tension of that in turning various types this spring.

In Figures 4 and 5 there is illustrated another embodiment oi the invention as a small size unit designed for use in connection with centers too small for the unit illustrated in Figure 3.

In this embodiment, as illustrated in Figures 2 and 4, there is provided the spindle body 51 which is closed at its rear end at 59 and'which is formed at its forward end to provide the circular head 59. This body has formed therein the straight bore 60 for the reception oi the centering pin 6I, the forward end of which is pointed at at 62 for engagement with the work.

The rear end oi the passage or bore 60 is enlarged slightly to iorm the fluid cushion chamber 83 and in this chamber is housed the expansion spring 64 which engages between the rear wall 58 of the body and the centering spur 65 which has contact with the longitudinal center of the rear end o! the pin as shown. This spring normally urges the pin 6I forwardly to a predetermined position. y

In the previously described forms or embodiments of the invention the axially movable parts such as the sleeve 29 and the pin 43 are engaged by encircling packings, the packing for the pin 43, in Figure 3, being designated 66. Likewise in the embodiment of the invention shown in Figure 4 there is also provided a packing which is designated 61 and which is carried by the forward end of the body to encircle the pin 6| and preventthe leakage of uld from the chamber 83, around the pin.

'I'he head portion 59 of the spindle body has formed therein the annular iluid chamber 88 from which lead inwardly to the bore 60, the passages 89 and 1t. lach of these passages 88 and 19 communicates with a channel 'll formed in the wall of the bore 6u between the passages 89 and 1B and the chamber 63. By means of these channels uid may now from the chamber 83 along one channel to the passage 69 into the reservoir 88 and back from the reservoir through the passage l and the adjacent channel ll into the chamber 83.

The passage t9 is the pressure relief passage and is controlled by the relief valve 'I2 which is maintained seated by the expansion spring 13. This spring is interposed between the valve 'I2 and the screw lt which is threaded into the head 59 as illustrated and which serves to maintain the spring at a desired pressure against the valve.

In the passage 'it suitable means is provided to form a valve seat l5 upon which ls engaged the valve 'E6 which opens toward the end of the passage lt in communication with the adjacent channel li. The relief valve 12 opens away from the adjacent channel li and therefore, as will be readily apparent, this valve will only permit the dow of fluid from the cushion chamber 63 back to the reservoir 6B while the valve 16 permits the ilow of fluid from the reservoir back to the cushion chamber.

In Figure 6, there is illustrated an embodiment of the present invention mounted in a tail stock post ll, with means for indicating the amount of Y pressure which the center is sustaining at all times. Y

In this construction there is iixed in the post ll the axially movable body 'i8 in which is formed from the forward end, the axial bore '19 which extends throughout a portion of the length of the body and stops at the wall 80 which forms the inner end of the bore and adjacent which the bore is slightly enlarged to provide the fluid cushion chamber 8l.

Slidably supported in the bore 19 is the ax ially movable plunger s2 which corresponds to the axially movable pins El and i3 except that this plunger. instead of having an integral center point, has a tapered socket 83. formed in its forward end to receive the tapered pin Bli which has at its forward end the point 85 for engagement with the work. u

Between the inner end of the axially movable plunger di and the wall 80, is interposed the expension spring at which normally urges the plunger and the pin carried thereby, forwardly to a. desired working position.

The rear end of the body 18 in addition to havlng formed therein a iiuid relief chamber 81 and a fluid reservoir at which are in communication with the chamber ill through the valve controlled passages 39 and Sil, as in the embodiments illustrated in Figures 2 and 3, has formed longitudi nally thereof the huid passage 9il which at its forward end opens into the fluid cushion chamber tl and at its rear end opens to the rear of the body i8. To the rear end of this passage Sl is attached the tube 92 of a. pressure gauge 93.

'I'he body 'la also has integrally connected therewith the threaded nut 9d which is positioned in a suitable recess in the post Tl to have threaded engagement with the adjusting screw 95 which is swivelly mounted in the customary manner, in

the post, so that as the screw is turned to the' right or to the left the spindle unit will be advanced or retracted as desired.

with the construction shown in Figure 6 it will be readily apparent that when the tail stock spindle is moved forwardly into engagement with a piece of work the gauge 93 will show the amount of pressure imposed upon the work by the point 85. 'I'hus after the work has been mounted in position and secured with the proper pressure as indicated by the gauge, the operator will be constantly advised Vof any increase or decrease of pressure due to heating oi the work or cooling thereof.

It will be readily apparent from the foregoing description of the several embodiments of the yieldable fluid cushion tail stock spindle when any one of the spindles is in use any increase in the dimensions of thework between the head stock and tail stock point will force the tail stock point rearwardly against the fluid cushion and when such pressure increases to a certain point the relief valve will be forced open allowing some of the fluid to pass through into Athe uid reservoir. In each case when such pressure and rearward movement of the point occurs, such movement will also be opposed by the expansion spring behind the point so that when the work cools the point will be forced to follow it back during its contraction, by the compressed spring. At the same time the forward movement of the point will draw into the cushion chamber from the reservoir, an amount of iiuid equal to that forced out when the point was moved rearwardly.

It will be seen from the foregoing that with the present invention in any one of its several eln-V bodiments here described.. a substantially constant pressure will be maintained upon the work in the lathe at all times regardless of changes in the dimensions of the work due to expansion or contraction and consequently danger of warping or bending the work is avoided andthere is also avoided any wobbling of the work while it is rotating. i

I claim:

1. A lathe tail stock spindle unit comprising, an elongated body having a longitudinal bore formed therein and. opening through one end only, the inner end of the bore forming a fluid cushion chamber, a fluid reservoir formed in the body, valve controlled ports leading to and from the reservoir from and to the cushion chamber a reciprocable member snugly tting in the bore for pressure at its inner end against fluid filling said chamber, and means at the outer end of the member for contact with a piece of work.

2. A yieldable lathe spindle unit comprising, a body adapted for mounting in a lathe tail stock and having a bore and designed to be supported with the bore co-axial with the lathe centers, a pointed center body supported in said bore for reciprocal axial movement therein, the inner end of the bore forming a cushion fluid chamber, resilient means in the chamber normally urgingl movement of the center body outwardly from the chamber, a fluid supply reservoir formi-ng a part of the body, having valve controlled inlet communication with the chamber, and a valve controlled outlet leading from the chamber to the reservoir.

3. A lathe lspindle unit'of the character stated, comprising a body designed to be supported in a tail stock, the body being of substantial length and having a bore formed therein from one end and extending through the maior portion of the length of the body, the bore at its inner end being enlarged to form a iiuid chamber, an elongated member supported in said bore and terminating at its inner end adjacent the enlarged portion of the bore, the inner end oi said elongated memthe 7. A lathe spindle structure of the character stated, comprising an elongated body adapted to be mounted in a tail stock and having a bore to ythe reservoir, a spring controlled valve normally resisting movement of the fluid from the chamber into the reservoir, and a valve controlled fluid passage between the reservoir and the fluid chamber` for admitting fluid from the reservoir into the chamber.

4. A lathe spindle unit of the character set forth in claim 3 in which said reservoir is formed and means for varying the degree of resistance offered by the first mentioned valve to the passage of fluid from the chamber to the reservoir.

5. A tail stock spindle of the character stated, comprising an elongated body adapted to be mounted in a lathe tail stock and having an axial bore formed therein from one end a-nd terminating short of the other end, a reciprocable member supported in said bore for longitudinal movement and carrying a work engaging point at its outer end, the inner end of the reciprocable member terminating short of the inner end of the bore whereby to provide a uid cushion chamber, a spring member within said chamber between the inner end of said reciprocable member and the inner end wall of the bore and normally urging said member outwardly, means forming a fluid reservoir within the body. a'valved inlet from the reservoir to the chamber, an outlet passage leading from the chamber into the reservoir, a

lspring pressed valve controlling the flow of fluid from the chamber through said outlet to the res.- ervoir, and a pressure gauge carried by the body and having a tubular communication with said chamber and adapted to register the fluid pressure in said chamber.

6. A tail stock spindle of the character stated,

comprising an elongated spindle body adapted tov be mounted in the tall stock having a bore formed therein from one end and terminating short of the other end of the body. a sleeve slidably positioned in said bore and closed at *ts inner end,

the inner end of the sleeve being in spaced relation with theinner end wall of the bore to form a fluid cushion chamber, an arbor within the sleeve and having a head upon its outer end within and closing the outer end of the sleeve, said head terminating in a point, bearings rotatably supporting-the arbor in the sleeve, resilient means within fluid chamber between the inner end of the sleeve and the inner end of the bore and normally urging the sleeve outwardly, a fluid reservoir formed in the body, a valve controlled passage between the reservoir and the chamber for admitting fluid into the chamber from tne reservoir, a relief passage leading from the chamber into the reservoir. and a spring pressed valve controlling the flow of fluid through the relief passage from the chamber to the reservoir.

formed therein from one end and terminating in the body short of the other end thereof, a member extending into said bore and terminating at its' inner end short of the inner end wall of the bore to form a fluid cushion chamber, a work engaging point at the outerend of said member, spring means within said chamber between the inner end wall of the bore and the inner end of the member for normally resisting inward movevthrough said relief passage from the ment of the member, a fluid reservoir within the body, a valve controlled passage between the reservoir and the chamber for admitting fluid from the reservoir into the chamber, a relief passage leading from` the chamber into the reservoir, a spring pressed valve controlling the flow of fluid chamber to the reservoir, and a packing secured to the body at the end through which the bore opens and encircling the member inserted into the bore, for preventing leakage of fluid outwardly around said member.

8. A spindle structure as set forth in claim '1, in which said fluid reservoir is formed in the body at the end thereof remote from the reclprocable member.

9. A spindle structure as set forth in claim 7, in which said fluid reservoir is formed in the body at the end thereof through which the bore opens and in which the valve controlled passage and the relief passage are, in part, comprised of channels formed longitudinally in the wall of the bore for conveying the fluid from the compression chamber to the reservoir at the end of the body remote from said chamber.

10. A spindle unit of the character stated comprising an elongated body having a bore formed longitudinally therein from one end and terminating short of the other end, the body at the said one end beingcircumferentially enlarged to form a head. said head having a circular fluid reservoir formed therein around the bore and communicating with the bore through two passages, said bore having the wall thereof provided with two longitudinal channels each communicating at one end with a passage, an elongated member supported in the passage for reciprocal movement and terminating at-its inner end short oi' the inner end wall of the bore whereby to provide a fluid cushion chamber, each of said channels communicating at its other end with said chamber, said member being pointed at its outer end for engagement with a piece of work, a valve controlling the movement of fluid from said reservoir through one passage and the adjacent channel to the pressure chamber, a spring pressed valve controlling the now of fluid from the chamber through the other channel and passage into the reservoir, and resilient means in said chamber between the inner endof said member and the inner end of the boro and resisting inward movement of the member in the bore.

JESSE C. GALLOWAY. 

